The present invention concerns signal analysis of microwave and radio frequency signals and pertains particularly to reduce the occurrence of spurs when analyzing signals.
When using a signal analyzer, such as a vector network analyzer, to measure operation of a converter, spurious responses can be generated by feed through from a local oscillator or by harmonics of the local oscillator mixing with internal receiver components in the network analyzer. Depending on the isolation between a radio frequency signal source and intermediate frequency signal generated by the converter, there can also be generation of radio frequency related spurs.
Filtering can be inserted around the converter to reduce the potential for spurs on the signal analyzer display. However, insertion of the filters is inconvenient and is not automatically performed by the signal analyzer. Additionally, when several different frequency bands are being measured, many different filters are required. These filters need to be switched in or out as needed and can contribute errors and uncertainties to the measurements.